Human beings are bad at making rational decisions and finding happiness. But these hiccups make for good reading, as is clear from the explosion of books on the subject. Joining the fray is “The Consuming Instinct” by Gad Saad, which considers human behaviour through a lens of biology and natural selection. He offers reassurance that some of man’s odder impulses, from high-stakes gambling to bungee-jumping or wearing stiletto heels, are rooted in evolutionary necessity.